a. Field of the Invention
The invention relates to an audio transducer, such as a speaker to transduce an electrical audio signal into acoustic sound or a receiver to transduce an acoustic sound into an electrical audio signal. This invention furthermore relates to a micro speaker optimized for high acoustic output and located within a small volume of a mobile device, such as a mobile phone, a tablet, a gaming device, a notebook or similar device.
b. Background Art
Prior art micro speakers are housed within an enclosure that provides a back volume for the speaker. Often the back volume is filled with an adsorber material which leads to an apparent virtual enlargement of the back volume. The adsorber serves to lower the resonant frequency of the speaker to a value that can only be achieved with a larger back volume in the absence of an adsorber. In prior art speakers, the enclosure may be filled with an adsorber through a small hole which leads to uneven or incomplete filling of the enclosure with the adsorber, which results in a decreased sound quality.